From: Ian Lance Taylor <ian@airs.com>
To: Bahadir Balban <bahadir.balban@gmail.com>
Cc: binutils@sources.redhat.com
Subject: Re: what are weak external symbols?
Date: Mon, 28 Mar 2005 14:19:00 -0000 [thread overview]
Message-ID: <m3r7i0wmzp.fsf@gossamer.airs.com> (raw)
In-Reply-To: <7ac1e90c0503261346244d052f@mail.gmail.com>
Bahadir Balban <bahadir.balban@gmail.com> writes:
> In summary it says that weak external symbols is a concept to avoid
> linking with unused parts of a library. The printf example is given:
> floating-point routines (namely fcvt) are referred as weak references
> by printf, such that when printf is used in a routine that didn't use
> fcvt, reference to fcvt resolves to zero and no error is produced from
> this.
>
> Now the questions:
>
> 1) Is my summary above correct?
Pretty much. Instead of "a routine that didn't use fcvt" I would say
"a program that didn't use fcvt."
> 2) Is this a case such that, these fcvt routines are explicitly
> defined in printf as weak references? If so, how do you define it as
> such in C source? Or perhaps you use a linker flag when you create the
> library?
Search for weak here:
http://gcc.gnu.org/onlinedocs/gcc-3.4.3/gcc/Function-Attributes.html#Function-Attributes
Other compilers have other mechanisms.
Ian
prev parent reply other threads:[~2005-03-28 1:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-28 2:08 Bahadir Balban
2005-03-28 14:19 ` Ian Lance Taylor [this message]
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